Fuel charge for internalcombustion engines



g- 7, 1951 A. T. COLWELL ETAL FUEL CHARGE FOR INTERNAL-COMBUSTIbN ENGINES Filed March 8, 1948 ADDITIVE m FUEL 22.55am: twoama i Patented Aug. 7, 195i FUEL CHARGE FOR INTERNAL- COMBUSTION ENGINES Archie T. Colwell, Cleveland, and Milton S. Roush,

Painesville, Ohio, assignors to Thompson Products, Inc., Cleveland, Ohio, a corporation of Ohio Application March s, 1948, Serial No. 13,556

4 Claims.

The present invention relates to internal combustion engine fuel charges which eliminate and prevent formation of deposits on the engine parts. The invention includes methods of introducing the fuel charge into the engine.

More specifically, this invention provides a fuel charge comprising gasoline or other fuels in combination with an additive which prevents formation of and which eliminates deleterious deposits created by the heating or burning of the fuel as well as lubricating oil in the combustion chambers and fuel intakes of spark-type engines. The invention further relates to methods for forming the fuel charge and introducing the same into the engine, including the use of supplemental anti-detonant fuels such as monohydric alcohols and water containing the additive.

Heretofore, the presence of deleterious deposits of gum, carbon, and other fuel constituents, such as tetraethyl lead in leaded gasoline in the fuel intake and combustion chamber has been accepted as a naturalconsequence of the use of modern blended, highoctane gasolines. Such deposits are formed by the heat polymerization and incomplete combustion of the fuel-air mixture in the engine to form non-volatile gums and carbon black. The gums may become quite hard and flint-like and act as an adhesive to bind the carbon black to the interior surfaces of the combustion chamber as an agglomerate deposit. These deposits are initially present as a thin, varnish-like material upon the combustion chamber walls and the piston head. This varnish-like deposit is initially soluble in organic solvents. However, on continued operation of the engine, the deposits accumulate at an alarming rate and the deposit becomes a thick, black insoluble thermo-insulating layer upon the interior surperformance, a lowering of the octane requirements, and an elimination of pre-ignition due to the presence of the deposits. The fuel charge of this invention comprises a main hydrocarbon fuel and a minor amount of an additive which is a reaction product of alcohols and alkylene oxides. Such reaction products have the following generic structural formula:

where R1 and R3 are the same or different hydrogen, alkyl, aryl, alkaryl, or aralkyl radicals. R2 is one or more alkylene radicals, and n is greater than 4.

The fuel charge of the present invention may be introduced into the combustion chamber continuously during the operation of the engine by combining the additive directly with the fuel. Preferably, however, the fuel charge is introduced into the chamber only during those periods at which the hardest flint-like deposits are most likely to form, thereby effecting economies in the use of the additive. Thus, it is desirable to introduce the fuel charge into the engine when the engine is operating on a fuel-rich fuel-air mixture, or, in other words, when the engine is functioning at full throttle.

A metering device which is automatically controlled by the throttle valve setting of the engine -may be employed to introduce the additive into the main fuel-air mixture in metered amounts to form the fuel charge of the present invention metering unit or injector may be actuated by the faces of the combustion chamber and the piston head. I

It has been found that the hardest flint-like deposits are formed when the engine is operating at full throttle conditions, due to the higher operating temperatures and the increased fuel feed to the engine, which is necessary to provide these operating conditions.

The aforementioned deposits have a definite deleterious effect upon engine performance. It has been found that these deposits cause an increase in the octane requirements for border line detonation, power loss due to heat confined in the combustion chamber, and pre-ignition due to the over-heating of the fuel-air mixture in the combustion chamber.

The present invention now provides a fuel charge by means of which such deposits are eliminated with a consequent increase in engine manifold pressure.

The fuel charge of the present invention may contain supplementary fuels such as those containing alcohols, water, and anti-detonants such as tetraethyl lead, monomethyl aniline, and the like. These supplementary fuels may be introduced into the main fuel stream by means of metering devices such as those above described. The additives of the present invention are compatible with such supplementary fuels and a mixture of additive and supplementary fuel may be added to the fuel stream from a common source through a common metering device to provide an efficient, unitary injection system by means of which the octane rating of the gasoline may be raised and any carbon deposits within the combustion chamber eliminated by employing the supplementary fuel and additive only at full throttle operation of the engine.

It is, therefore, an important object of the present invention to provide a fuel charge comprising a hydrocarbon fuel and an additive for preventing formation of as well as for eliminating previously formed deleterious deposits normally caused by heating and burning the fuel in internal combustion engines.

It is another important object of the present invention to provide a, method of eliminating and preventing the formation of deleterious deposits in internal combustion engines by injecting a fuel charge comprising a mixture of a hydrocarbon fuel and an additive effective to prevent the formation of such deposits, said additive having the structural formula:

in which R1 and Re are the same or different hydrogen, alkyl, aryl, alkaryl or aralkyl radicals, R2 is one or more alkylene radicals, and n is greater than 4.

A further object is to provide a method of preventing formation of deleterious deposits in an internal combustion'engine by incorporating an additive such as specified above into the com bustion chamber only when the engine is operating under detonating conditions.

It is a still further important object of the present invention to provide a fuel charge composed of gasoline, a monohydric alcohol, water, an anti-detonant and a minor proportion of an additive having the structural formula:

in which R1 and R3 are the same or different hydrogen, alkyl, aryl, alkaryl or aralkyl radicals, R2 is one or more alkylene radicals, and 11, is greater than 4.

Other and'further objects of the present invention will be apparent to those skilled in the art from the following detailed description of the annexed sheet of drawings which illustrates apparatus for forming the fuel charge of this invention and for carrying out the method of the invention together with a graph showing effects of use of the invention;

- On the drawings:

Figure 1 is a diagrammatic, vertical cross-sectional view, with parts in elevation, of an internal combustion engine and fuel supply and intake assembly equipped with a'fuel injector or metering device for supplying additives of the present invention to the intake manifold of the engine and to the combustion chamber of the engine.

Figure 2 is a graph diagrammatically illustrating the percent deposit reduction obtained by the use of the fuel charge of the present invention as a function of the amount of additive present in the charge.

As shown on the drawings:

Figure 1, an internal combustion engine It is equipped with the customary air and fuelcharging assembly and is supplied with a hydrocarbon fuel, such as gasoline, from tank I I, the fuel passing through main fuel line l2 to carburetor I3. In the carburetor I3, the gasoline is commingled with an amount of air entering the system through air intake port H. The fuelair mixture is introduced into the engine III through intake manifold IS, the introduction of the fuel-air mixture into the combustion cham her It being controlled by intake valve l I. A piston I8 is mounted in the combustion chamber l6 and is connected through connecting rod Is to a conventional crankshaft (not shown). A spark plug 20 is mounted in one cylinder wall 2| of combustion chamber It to ignite a fuel-air mixture contained therein. The gases of com ustion are discharged through the exhaust manifold 22 under control of the exhaust valve 23. Both the intake valve l1 and the exhaust valve 23 are mounted in a cylinder head 24.

A mounting block 25 is interposed between the carburetor I3 and the intake manifold l5. A relatively small tank 28 is provided for the additive of the present invention and/or supplemem tary anti-detonant fuel for introduction into the combustion chamber of the engine in combination with the main fuel contained in tank ll.

The tank 25 is connected to metering device 21 through a supplementary fuel line 23 equipped with a valve 29. The metering device 21 includes a float 3|! controlling inlet valve 3| to control the flow of additive into the device 21. The float 33 is mounted in float chamber 32 which is vented to the atmosphere at 32a and additive under atmospheric pressure in the float chamber flows through a passage 33 to a metering valve 34 which is controlled by a. diaphragm 35. Additive flowing past the metering valve passes through the passageway 35 to a nozzle 3! carried by the block 25 and opening downstream in the intake manifold IS.

A spring 38 is mounted in spring chamber 33 which is vented through passageway I. to the interior of block 25. The spring 33 is adjusted by means of adjusting mechanism ll to bear against the diaphragm 29 tending to open the metering valve 3i. Since it is desired to feed the additive and/or supplementary fuel contained in tank 26 to the engine only during those periods Of operation during which the majority of carbon deposition will occur within the combustion chamber, and since such periods of engine operation are accompanied by a decreased vacuum or increased pressure in the inlet IS, the spring 38 is effective tomove the metering valve 3| toward open position, because the vacuum in the chamber 39 is insufficient to overcome the spring pressure. Additive and/or supplementary fuel is thereupon discharged through nozzle 31 in amounts determined by the opening of the metering valve. The fuel is discharged through the nozzle 31 to become intimately mixedin fine spray form with the main fuel and air mixture flowing through intake manifold l5. Upon a decrease in the intake manifold pressure and an increase in the vacuum in the spring chamber 33, the diaphragm 35 pulls the metering valve to closed position to interrupt the feed of additive and/or supplementary fuel.

The intake vacuum is a function of the degree of the opening of the throttle 42 which controls the flow of the main fuel and air stream into the engine Ill. As the setting of throttle controls both the flow of the main fuel from tank II and; the intake manifold pressure, and thereby the flow of additive or supplementary fuel through the metering device 21, it may be seen that the additive may be introduced through the metering device 21 during those periods when the harder flint-like deposits are most likely to form both in the intake assembly and inthe combustion chamber it due to the higher operating temperpolymerization of unsaturated constituents of the fuel. The gum and carbon deposits in the combustion chamber of the engine are most likely formed from lubricating oil in the combustion chamber. The lacquers deposited on the piston skirt and ring grooves can be formed from both the oil and the fuel.

As the operating temperature of the engine increases under full load or open throttle operating conditions, the intake assembly is further heated and the gum formation is accelerated both because of the increased temperature and the increased rate of fuel feed. These gums are relatively non-volatile and deposit mainly on the valve stem. At the same time, in the combustion chamber, the higher operating temperatures, the increased oil consumption, and the increased richness of the fuel-air charge necessary to operate the engine under full load, accelerate the carbon and gum deposits in the combustion chamber and the lacquer deposits on the piston skirt and rings.

We have found that an additive composition, in order to effectively prevent or eliminate the formation of the above-described deleterious deposits as a component of the fuel charge, must possess certain physical and chemical properties.

To be effective in the combustion chamber, the additive must be fairly non-volatile, have a low vapor pressure and be capable of condensation at the combustion surface temperatures. These temperatures vary from about 400 to 700 F. at the cylinder head to a value of approximately 1600 F. at the piston head. The additive must decompose at elevated temperatures to form completely volatile decomposition products in order that the additive itself will not form a deposit within the combustion chamber. Also, the additive composition must be able to wet the surface of the combustion chamber and of the piston head.

To be effective in the intake assembly of the engine, the additives should have a gum solvent action or a polymerization depressing effect upon the fuel unsaturates. The intake assembly operating temperatures are less than the temperatures in the combustion chamber, varying from atmospheric temperatures up to about 400 F.

It is, of course, important that neither the additive nor its decomposition products have a corrosive effect on the engine parts.

We have found that the reaction products of alcohols and alkylene oxides possess the properties above enumerated as necessary for such materials and are suitable additives for use in fuel charges of the present invention. Such reaction products have the following structural formula:

Those reaction products of alcohols and alkylene oxides having the above given structural formula in which R1 and R3 are the same or different hydrogen, alkyl, aryl, alkaryl or aralkyl radicals,

R2 is one or more alkylene radicals, and n is greater than 4, are particularly suitable for use in the present invention. Such compositions may be prepared as set forth in U. S. Patent No. 2,425,755 to F. H. Roberts et al. and Patent No. 2,425,845 to W. J. Toussaint et a1. These compositions are commercially available under the trade-mark Ucon and are manufactured by the Carbide and Carbon Chemical Corporation. We prefer to employ compounds having the above identified structural formula in which n is at least 10, or such compounds in which the average molecular weight is not less than 300.

Such high molecular weight compositions as are herein contemplated are generally mixtures of compounds in which mixtures the values for n and the molecular weight are average values only. For example, a composition formed by the reaction of butyl alcohol and 1,2-propylene oxide having a viscosity index of 144 (ASTMD-567-41) may have an average molecular weight of 1133 and a value of n of 18.4. The molecular weights of individual compounds present in this mixture may vary from about 1000 to about 1300, and the value for'n may vary from 15 to 20. The values for n and the molecular weights as given herein are merely average values for the entire composition, and should not be construed as a limitation upon the structure of individual components of the mixture.

Further, the radicals represented by R1, and R3, in the structural formula may vary in the individual compounds which constitute the mixture. For example, in the composition given above, individual compounds in which both R1 and R3 are each butyl radicals, other compounds in which both R1 and R3 are H radicals, or in which R1 and R3 are hydrogen and butyl radicals respectively may be obtained. Thus although an acetyl value may be obtained indicating that R1 is a butyl radical and R3 is a hydrogen radical, it is probable that in at least some of the individual components of the composition R1 and R3 are both butyl or hydrogen radicals. However, in

, the present invention, the specific composition of the individual components of the mixture are unimportant and the average values may be used to designate the compositions, since We have found that compounds in which R1 and R3 are the same or different hydrogen, alkyl, aryl, alkaryl or aralkyl groups are suitable for use as additives.

The fuels which may be employed in combination with these additives to form the fuel charge may be straight run gasoline, thermally cracked gasolines, or catalytically cracked gasolines, or blended fuels containing more than one type of gasoline. We have found that fuel charges entering the combustion chamber which contain from 0.1 to 10% additive in combination with such hydrocarbon fuels are effective to reduce the amount of deposit within the combustion chamber. We have found that fuel charges for ignition in the combustion chamber which contain from 0.5 to 5% additive are particularly desirable due to the more eflicient utilization of the additive at these concentrations. For example, we have found that the presence of 0.1 by weight of additive in the fuel charge of the present invention is effective to reduce the deposit formed in the combustion chamber by an amount equal to from 15 to 37% of the deposit formed in the absence of the additive. It is evident that the amount of additive employed when the additive is injected into the combustion 7 chamber intermittently will depend upon the operating conditions of the engine, or more specifically upon the total operating time at full throttle. j

We have found that the additives of the present invention are suitable for use with leaded gasolines. However, blended gasolines containing anti-detonants, such as tetraethyl lead, are ordinarily continuously fed into the engine dur=- ing all conditions of engine operation, although the use of the expensive anti-detonant is seldom required in internal combustion engines under normal engine operating conditions. Accordingly, we prefer to employ the additives as herein described in combination with supplementary fuels for injection into the internal combustion spark engine only when the engine is operating under detonating conditions. These detonating conditions in the engine coincide with those conditions under which the most harmful deposition of deleterious deposits occur in the engine. Consequently, it is feasible to simultaneously inject the additive and supplementary fuel into the main fuel stream and hence into the combustion chamber. Suitable supplementary fuels for use in conjunction with'the additives of this invention are those which contain from 30 to 90% by weight monohydric alcohol, to 65% by weight water, or high octane hydrocarbons and preferably small amounts of additional anti-detonant such as 0.1 to 15 cc. per gallon of tetraethyl lead, and/or from 5 to 20% by weight monomethyl aniline, iron or nickel carbonyl, glycols, benzene, phenols, xylidine and its homologues, and the like.

The fuel charge of the present invention has been found to be effective in the removal of as much as 88% of the deposits incurred upon the use of ordinary gasoline. The actual removal is considerably greater than indicated by the following experimental data. The small amount of deposit obtained upon use of the fuel charge is actually an oil and is not particularly objectionable since it does not cause sticking of the valves and piston and does not cause predetonation of the fuel-air mixture in the combustion chamber.

It has been found that the intermittent injection of the additives of the present invention results in the more effective use of that amount of additive'which is introduced. For example} we have found that the introduction of 2 /2 of a typical additive of this invention continuously during operation of the engine results in a 71.7% reduction in the amount of deposit formed in the combustion chamber. By introducing '2 /2% additive based on the amount of hydrocarbon fuel employed during only 25% of the operating time of the engine, we have obtained a 50.6% reduction in the amount of depositformed. In other words a 75% reduction in the amount of additive employed results in only a 21.1% increase in the amount of deposit formed in the combustion chamber.

Thus it may be. seen that the introduction of additive upon an intermittent schedule results in the more effective utilization of the depositinhibiting characteristics of the additive.

The following examples illustrate further details of the methods of this invention and the results obtained thereby.

EXAIMPLEI Five single-cylinder internal combustion marine-type spark-engines attached to generators, each generator having a rated output of 1000 watts, were set up to determine the deposit reduction obtained by .the use of the fuel charge of the present invention. Throughout the tests of this example the engines were run to obtain a generator output of 780 watts. The gasoline employed was a thermally cracked hydrocarbon stock having an octane rating of 65.5. The additive employed was a reaction product of a lower aliphatic alcohol such as butyl alcohol and 1,2- propylene oxide having a. molecular weight of approximately 1200, the compound containing an average of approximately 18 propylene units per molecule. For the continuous introduction of additive, as in test If hereinafter described, the

. additive was added in the indicated amounts to the fuel and the mixture of fuel and additive was fed directly into the engine carburetor. For the intermittent injection of the additive, as in tests III and IV, a pair of tanks were connected to the carburetor and valve means for controlling the flow of fuel from the tank to the carburetor were provided. One of the tanks was filled with hydrocarbon fuel containing the above-identified additive, while the other contained only the hydrocarbon fuel. These two fuels were fed into the carburetor of the engine in accordance with the schedules indicated in Table I with the indicated results. Table I indicates the testing conditions and the results obtained in tests I through IV. The amount of deposit obtained was deter- Table I Per Cent Deposit Tm Additive Schedule (Total Time 16 hrs) No. No. Additive mined duiialtlion Deposit 1 none no additive 8239 none 2 none 1,072 none I 3 none .dn 1,083 none 4 none 734 none 5 none 1, 492 none I t i 0 II 3 2% nstant addition of additive 305 71, 7 4 3 256 66. 2 a 4 776 47. 9 I a 5 I 20 minutes no additive m i g 20 minutes additive in specified amount and then repeat- 5 4 921 38. 3 a a 35-; 1 30 minutes no additive w i g 10 minutes additive in specified amount and then repeat 5 4 1, 401 0. 6

mined by disassembly of the engine, scraping the combustion chamber surfaces and the piston head and weighing the deposit thus obtained. It was found upon analysis that the amount of metal scraped from the chamber surfaces and piston head was negligible and had no efiect upon the results obtained. The deposit reduction was determined by dividing the difference between the deposit obtained in each test II, III and IV and the corresponding deposit of .test I by the weight of the deposit of testI expressing the result as percentage.

The results obtained on tests II, HI and IV are illustrated in the table comprising Figure 2 on the attached drawings as lines A, B and C respectively. It is to be noted from the test data that, in each instance, the maximum results were obtained by'employing a concentration of 2 additive based upon the total amount of fuel employed. It should also be noted that by a reduction in the amount of additive added to an amount equal to only 25% of that employed in test 11, a deposit increase of only 21.1% was obtained. Thus it may clearly be seen than an improved utilization of the deposit-inhibiting characteristics of the additive is obtained by intermittent injection of the additive into the main fuel stream.

EXAMPLE 2 To determine the extent of combustion chamber deposition under the test conditions of Example 1, while employing leaded gasoline, 2 cc. per gallon of tetraethyl lead were added to the thermally cracked gasoline employed in Example 1. The other test conditions were identical with those of Example 1, the same additive was injected continuously, and the results were determined in the same manner. Table II summarizes the test conditions and the results obtained upon the use of the additive in conjunction with leaded gasoline.

To determine the effect of engine load upon the eifectiveness of the fuel charge in the prevention of carbon deposits within the combustion chamber, the engine load was varied from a value of 200 watts to 950 watts by the insertion or removal of resistance in the generators attached to the engines. The other conditions of this example are identical to the conditions of Example 1, the same fuel and additive being employed, the additive being injected continuousLv into the engine. Table 3 summarizes the engine load conditions and the results obtained:

To determine the effect of the additives of the present invention when employed in combination with supplementary fuels containing a monohydric alcohol and water, a number of additives were employed with a supplementary fuel comprising a 50% solution of methanol in water. The additive was added to the supplementary fuel in an amount equivalent to 7% by weight of the total mixture. The mixture of supplementary fuel and additive is then injected continuously into the engine through a metering device 21 as illustrated in Figure 1. The amount of supplementary fuel added to the main hydrocarbon fuel was equivalent to about 15% of the total weight of the fuel. This gave an amount of additive present in the fuel equivalent to about 1% by weight. The fuel charge actually introduced into the engine thus contained approximately 7% water, 7% methanol, 1% additive,

and the balance gasoline. The additives employed are the reaction products of a mixture of ethylene and propylene oxides with an aliphatic alcohol. The molecular weights of the additives range from 355 to 3,120. The test conditions and the results obtained are summarized in Table IV:

Table IV Deposit Per Cent Additive Per Cent De sit Mol. Wt. Additive g Reite- Test N0.

355 None EXAMPLE 5 To determine the efiect of the additives of the present invention upon the amount of combustion chamber deposit obtained when the engine was run under a fluctuating load, the following conditions were employed. Five engines were set up as described in Example 1. The load upon the engines was varied so that each engine ran 30 minutes at a generator load of 200 watts and then 10 minutes under a load of 900 watts. The additive was introduced into the engine during the-high load cycle only in the 75 amounts given. The load was varied thus for 4Q 11' hours. The fuels and additives employed were those of Example 1. The test conditions and results are summarized in Table V.

It will, of course, be understood that various details'of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

'We claim as our invention:

1. A fuel charge for combustion in internal combustion engines comprising a hydrocarbon fuel and a minor amount of a reaction product of an alcohol and an alkylene oxide, the reaction product having the structural formula R1-O-[Ra-O]--Ra where R1 and R3 are selected from the group consisting of hydrogen, alkyl, aryl, aralkyl and alkaryl radicals, R2 is an alkylene radical and n is greater than 4.

[2. A fuel charge for. combustion in internal combustion engines comprising gasoline and from 0.1 to 10% by weight of a reaction product of an alcohol and an alkylene oxide, the reaction product having the structural formula R1-O[R20]n-R3 where R1 and R: are selected from the group consisting of hydrogen, alkyl, and aralkyl radicals, R: is an alkylene radical and n is greater than 4.

3. A fuel charge for injection into the combustion chambers of an internal combustion ensine and combustion therein when said engine is operating under full throttle conditions compris- 8 asoline, water, a monohydric alcohol, and a reaction product of an alcohol and an alkylene oxide, the reaction product having the structural formula RiO[RaO].R-i where R1 and R1 are selected from the group consisting of hydrogen, alkyl, aryl, aralkyl and alkaryl radicals, R: is an alkylene radical, and n is greater than 4.

4. A fuel charge for periodic injection into the combustion chamber of an internal combustion en ine and combustion therein when said engine is operating under detonation conditions consisting essentially of gasoline, water, a monohydric alcohol, an antidetonant, and a reaction product of an alcohol and alkylene oxide, the reaction product having the structural formula 'RiO[Ra0]n-R: where R1 and Rs are selected from the group consisting of hydrogen, alkyl, aryl, alkaryl, and aralkyl radicals, R: is an alkylene radical and u is greater than 4.

ARCHIE T. COLWELL. lflLTON S. ROUSH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,183,483 O'Hara May 16, 1916 1,467,222 Aseltine Sept. 4, 1923 1,506,166 Durrant Aug. 26, 1924 1,757,837 Johns May 6, 1930 1,758,897 Evans May 13, 1930 2,002,483 Kimball May 21, 1935 2,277,74 Eckel et al Mar. 3l, 1942 2,321,211 Johnson June 8, 1943 2,429,707 Catalano Oct. 28, 1947 OTHER. REFERENCES Russ, Ucon Synthetic Lubricants and Hydraulic Fluids, Symposium on Synthetic Lubricants, Special Technical Publication No. 77, Fiftieth Annual Meeting ASTM, June 16-20, 1947, pages 3-11. V

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1. A FUEL CHARGE FOR COMBUSTION IN INTERNAL COMBUSTION ENGINES COMPRISING A HYDROCARBON FUEL AND A MINOR AMOUNT OF A REACTION PRODUCT OF AN ALCOHOL AND AN ALKYLENE OXIDE, THE REACTION PRODUCT HAVING THE STRUCTURAL FORMULA R1-O-(R2-O)N-R3 WHERE R1 AND R3 ARE SELECTED FROM THE GROUP CONSISTING OF HYDROGEN, ALKYL, ARYL, ARALKYL AND ALKARYL RADICALS, R2 IS AN ALKYLENE RADICAL AND N IS GREATER THAN
 4. 